Rock duster



Nov. 22, 1949 A. J. GURNEY ET AL 2,489,090

ROCK DUSTER Filed July 2, 1945 3 Sheets-Sheet l ZSnventors N fllbefii' J Gunney 4 Glenn llGumzey (Ittornegs Nov. 22, 1949 A. J. GURNEY ETAL 2,489,090

ROCK DUSTER Filed July 2, 1945 s Sheets-Sheet .2

3nven1tors W Gttonlegs Nov. 22, 1949 A. J. GURNEY ET AL ROCK DUSTER 5 Sh eets- Sheet 3.

Filed July 2, 1945 3 Wu w G DR w GFU. J D Mn? ,6 ML AG Patented Nov. 22,1949 I UNITED STATES PATENT OFFICE.

ROCK DUSTER Application July 2, 1945, Serial No. 602,700

4 Claims.

The invention relates to apparatus for spraying rock dust in coal mine tunnels and similar places, to cover or mix with the coal dust upon the floors, walls and ceilings to prevent explosion of the coal dust.

It is common practice to spray the interiors of mine tunnels and the like with apparatus of this general character, and such apparatus as is at present used for this purpose comprises generally a hopper containing the rock dust and having screw means in its lower portion for feeding the rock dust to a feed tube or pipe through which an air blast is passed for spraying the rock dust from a suitable nozzle connected to said feed tube.

Difficulty has been experienced in the past by the rock dust packing and arching over the feed screw in the bottom of the hopper, so the uniform feeding of the rock dust to the feed tube is frequently interrupted, requiring manual breaking up of the caked and arched rock dust from time to time.

In order to overcome this difficulty the structure disclosed in Gurney Patent No. 1,781,509 of November 11, 1930, was produced, wherein a pair of parallel feed screws were located in the bottom of the hopper and an agitator shaft was located above the screws and provided with a multiplicity of radial pins or fingers for continually breaking up any packed or caked portions of the rock dust and preventing it from arching above the feed screws.

Such construction overcame the difiiculty to a considerable extent, but the agitator shaft was found to be dangerous as there was a possibility of workmen getting a glove or sleeve caught upon the rotating, radial fingers thereof, causing injury to the workman.

Another difliculty encounted in the general type of rock dusters now in common use is in the connection of pipes and fittings from the blower to the feed tube. It is also pointed out that in the present form of rock dust a low speed screw is used for feeding the rock dust through the hopper to the feed tube, and it is thought that the tendency of the rock dust to pack and arch above the feed screw may be at least partly due to the slow movement of the screw, which in ordinary practice rotates at less than one hundred revolutions a minute, generally at a speed of about sixty-six revolutions per minute.

The present invention has for its object the provision of a rock duster which overcomes the difficulties and objections above referred to.

A specific object of the invention is to provide a rock duster which prevents packing and arching of the rock dust above the feed screw.

Another object is to provide a rock duster in which an agitator shaft is not required above the feed screw to prevent caking or packing of the rock dust.

A further object of the invention is to provide a rock duster having a single high speed feed screw located through the hopper for uniformly feeding rock dust to the feed tube.

A still further object is to provide a rock cluster in which an air chamber is located along one wall of the hopper and connected at one end to the blower and at its other end to the feed tube, whereby the usual pipes and fittings between the blower and the feed tube are dispensed with and a continual blast of air is passed along one wall of the hopper, producing an agitation of the rock dust within the hopper and tending to prevent packing or arching thereof above the feed screw.

Another object of the invention is to provide a rock duster having a check valve located in the feed tube to prevent back pressure of the air blast into the hopper.

The above objects, together with others which will be apparent from the drawings and following description, or which may be later referred to,

may be attained by constructing the improved rock cluster in the manner illustrated in the accompanying drawings, showing a preferred embodiment of the invention, in which:

Figure 1 is a top plan view of the improved rock duster;

Fig. 2 a vertical, longitudinal section through the rock duster, taken as on the line 2--2, Fig. 1;

Fig. 3 an enlarged, vertical, transverse section through the rock duster, taken as on the line 3-3, Fig. 1;

Fig. 4 an enlarged sectional view through the gear housing, taken as on the line 4-4, Fig. 1; and,

Fig. 5 an enlarged, horizontal, longitudinal section through the feed tube, showing the check valve therein, taken as on the line 5, Fig. 2.

The rock duster is designed to be moved through mine tunnels or the like, and may be arranged to be conveyed upon a railroad track by means of a locomotive, and for this purpose the apparatus is mounted upon a carriage which may comprise the frame II) in which are journalled axles ll upon which are mounted the flanged wheels [2 adapted to run upon rails 53.

A hopper is mounted upon the frame, for containing a supply of rock dust, this hopper preferably being of substantially V-shape as best shown in Fig. 3, and comprising-the downwardly, converging side walls I4 and the front and rear walls l5 and It respectively.

Overhanging, horizontal shelves I! may be formed at the upper ends of the side walls of the shaft 3'3, within the housing 36, for manually engaging or disengaging the sprocket wheel 31 with the shaft 34, this clutch being operated through the vertical shaft 4! and hand lever 48. Thus the feed screw may be started or stopped at any time during the operation of the motor.

The blower shaft 49 may also be provided with a flexible coupling 50 and extends into the gear housing 36 having the sprocket 5i fixed thereon and connected as by the chain 52 with the sprocket 53 upon the motor shaft Ml whereby the blower will be operated continuously during the operation of themotor.

The feed screw-22 being? connected directly to the motor is driven at high speed, preferably about twelve hundred revolutions per minute.

hopper, terminating in the depending reinforcing in an air chamber l9 located upon one sideof the.

hopper and enclosed by one side wall M, of the hopper and a wall parallel theretmthe bottom wall 2|, a portion 0f the adjacent shelf I? forming the top wall of the air chamber and extensions of the front and rear walls 15 and it of thehopper-forming the front and rear walls of the air chamber.

A single high speed feed screw 22 is located longitudinally through the lower portion of the hopper, theshaft thereof being journalled through the rear wall Ni of'the hopper as indicated at 23 in Fig. 2, while the forward end of the feed screw is extended through an opening 24in the front wall l5 of the hopper and into the inner tube 25 located within the feed tube 25 which is connected to the front wall of the hopper.

A spider 2! is fixed upon the forward end of the inner tube 25 and has a bearing 28 formed thereon within'which is'slida'bly mounted the stem'29' of the check valve 3U which is normally seated in the end'of the'inne'r tube 25 as by the spring 3|;

The feed tube 26 extends slightly beyond the inner tube 25 andis provided with the flanged end 32 to which a nozzle of any usual and well known design, such for'instance as indicated in the Gurney Patent No. 1,781,509 above referred to,

may be attached for spraying the rock dust within a mine tunnelor the like. The feed tube 26 has the elbow 33 formed thereon which communicates with the air chamber [9 as best shown in Fig. 5.

The shaft 34 of the feed screw may have a flexible coupling 35 thereon and is extended into the gear housing 36 mounted near the rear portion of the frame It, a sprocket wheel 3'! being fixed upon said shaft within the housing and connected as by the chain 38 with a sprocket 39 upon'the shaft 40 of the 'motor il, a flexible cou pling' 42 being. preferably/located in the motor shaft also. A starter 43 iszprovided upon the rear portion of the frame ill, for the motor M.

A blower 44 is mounted adjacent the rear end of the hopper and is connected,.as by the pipe 45,

to the air chamber l9 so that when the blower is being operated a continuous blast of air is passing through the air chamber l9 and into and through the feed tube 26, picking up rock dust which is fed into the feed tube by means of the feed screw and blowing the same through the nozzle for spraying the ceilings, walls and floors of coal mines, tunnels and thelike.

A clutch 46 is provided upon the feed screw The continual blast of air passing through the air chamber It has a tendency to vibrate the ,adjacent side Wall 54 of the hopper, and it has been found in actual practice that this vibration of the hopper-together with the high speed of the screw produces sufilcient agitation of the rock dust within the'hopper to prevent the same from packing or arching over the screw, and dispenses with the necessity of providing twin screws and an agitating shaft, as, hasbeen customaryin the past.

We claim:

1. A rock dustercomprisinga. hopper, afeed screw in the lower portion of the hopper, means for rotating the feed. screw, afeed tubecommunicating with one end of the hopper, .the. feed screw being exvended into said feed tube, .an air chamber formed along oneside of the hopper and communicating, at its forward end with the feed tube, the adjacent side wallof' thehopper form ing one side wall of the air. chamber, and means for passing an air blast throughsaid'air chamber to the feed tube s0 as to vibrate said adjacent side wall of the hopper.

2. A rock duster comprising. a hopper; a. feed screw in the lower portion of the hopper, means for rotating the feed screw, a feed tube communicating with'one end of the hopper, the feed screw being extended into said feed tube; an air chamber of a height and length correspond ing to the height and length of the hopper formed along one side of the hopper and communicating at its forward'end with the feed tube the adjacent side wall of the hopper forming one side wall of the air chamber, and means for passing an air blast through said air chamber to the feed tube so as to Vibratesaid adjacent side wall of the hopper.

3. A. rock duster comprising a hopper, a feed screw in the lower portion of thehopper, a motor; sprocket and chain gearing connecting the feed screw directly to the motor for rotating the feed screw at a speed of about R. 2-; Mn a feed tube communicating with one end'of the hopper; the feed screw being extended into said feed tube, an air'chamber formed along one side of the hopper and commnnicatingat its forward end with the feed tube, the adjacent side wall of the hopper forming one side wall of the air chamber, and means for passing an air blast through said chamber to the feed tube so as to vibrate said adjacent side wall of the hopper.

4. A rock duster comprising a hopper, a feed screwin the lower portion of the hopper, afeed tube communicating with the forward end of the hoppenthe feed screw being extended into said feed tube, an chamber formed along one side wall of the hopper and coextensive there= with, said air chamber communicatingat its for 5 ward end with the feed tube the adjacent side Wall of the hopper forming on side wall of the air chamber, a blower communicating with the rear end of the air chamber for passing an air blast through said air chamber to the feed tube 5 so as to vibrate said adjacent side wall of the hopper, a motor, sprocket and chain gearing connecting the motor to the blower and sprocket and chain gearing connecting the motor directly to the feed screw.

ALBERT J. GURNEY.

GLENN D. GURNEY.

REFERENCES CITED The following references are of record in the 15 file of this patent:

Number UNITED STATES PATENTS Name Date Johnston Mar. 31, 1891 Filson Apr. 28, 1903 Woodley May 23, 1916 Bernert Oct. 10, 1916 Reed Apr.. 12, 1921 Grindle May 27, 1924 Tainton Jan. 26, 1926 Kemmer Apr. 5, 1932 Gurney Sept. 8, 1936 Morrow July 21, 1942 Baker Aug. 15, 1944 

